LEDs are semiconductor photonic devices that emit light when a voltage is applied. LEDs have increasingly gained popularity due to favorable characteristics such as small device size, long lifetime, efficient energy consumption, and good durability and reliability. In recent years, LEDs have been deployed in various applications, including indicators, light sensors, traffic lights, broadband data transmission, back light unit for LCD displays, and other suitable illumination apparatuses. For example, LEDs are often used in illumination apparatuses provided to replace conventional incandescent light bulbs, such as those used in a typical lamp.
However, existing LEDs still have drawbacks. For example, conventional high voltage LEDs may be configured to handle a high voltage (e.g., a few hundred volts), but they may suffer from problems such as poor heat dissipation and frequency electrical failures. A conventional flip chip LEDs may have better heat dissipation than the conventional high voltage LEDs, but conventional flip chip LEDs cannot handle high voltages and have poor light extraction efficiency. And in addition to some of these problems discussed above, other types of LEDs may also require difficult dicing processes.
Therefore, although existing LEDs have been generally adequate for their intended purposes, they have not been entirely satisfactory in every aspect. High voltage LEDs with better heat dissipation, more efficient light extraction, and more robust electrical connections continue to be sought.
A lighting apparatus includes a polygon die including a plurality of light-emitting diodes (LEDs), and a submount to which each of the LEDs is coupled. Each LED includes a plurality of epi-layers which contains a p-type layer, an n-type layer, and a multiple quantum well (MQW) disposed between the p-type layer and the n-type layer, and a p-type electrode and an n-type electrode which are electrically coupled to the p-type layer and the n-type layer, respectively. The p-type and the n-type electrodes are located between the submount and the epi-layers. The submount contains a plurality of conductive elements configured to electrically couple at least a portion of the plurality of LEDs in series. At least some of the plurality of LEDs have non-rectangular top view shapes.